This invention relates generally to a paper machine, and more particularly, to a system and method for predicting web break sensitivity in the paper machine and isolating machine variables affecting the predicted web break sensitivity.
A paper machine of the Fourdrinier-type typically comprises a wet-end section, a press section, and a dry-end section. At the wet-end section, the papermaking fibers are uniformly distributed onto a moving forming wire. The moving wire forms the fibers into a sheet and enables pulp furnish to drain by gravity and dewater by suction. The sheet enters the press section and is conveyed through a series of presses where additional water is removed and the web is consolidated (i.e., the fibers are forced into more intimate contact). At the dry-end section, most of the remaining water in the web is evaporated and fiber bonding develops as the paper contacts a series of steam-heated cylinders. The web is then pressed between metal rolls to reduce thickness and smooth the surface and wound onto a reel.
A problem associated with the Fourdrinier-type paper machine is that the paper web is prone to break at both the wet-end section of the machine and at the dry-end section. Web breaks at the wet-end section, which typically occur at or near the site of its center roll, occur more often than breaks at the dry-end section. Dry-end breaks are relatively better understood, while wet-end breaks are harder to explain in terms of causes and are harder to predict and/or control. Web breaks at the wet-end section can occur as much 15 times in a single day. Typically, for a fully-operational paper machine there may be as much as 35 web breaks at the wet-end section of the paper machine in a month. The average production time lost as a result of these web breaks is about 1.6 hours per day. Considering that each paper machine operates continuously 24 hours a day, 365 days a year, the downtime associated with the web breaks translates to about 6.66% of the paper machine""s annual production, which results in a significant reduction in revenue to a paper manufacturer. Therefore, there is a need to reduce the amount of web breaks occurring in the wet-end section of a paper machine.
This invention has developed a system and method for predicting web breaks in either the wet-end section or the dry-end section of the paper machine. In addition, this invention is able to isolate the root cause of any of the predicted web breaks. Thus, in this invention there is provided a plurality of sensors for obtaining a plurality of measurements from the paper machine. Each of the plurality of measurements relate to a paper machine variable. A processor processes each of the plurality of measurements into break sensitivity data. A break predictor responsive to the processor, predicts a web break sensitivity within the paper machine from the plurality of processed measurements.